My confusion stems from a an led that shows: Input(DC): 600mA-700mA / 3V-3.4V.
the product suggests a constant current led driver (same brand as LED) that shows: Output: Current 600mA (Constant) ; Voltage 18-34V
In researching I have read that excessive current will burn out the LED and over time as the battery drains the amps drawn gets smaller resulting in the need for a constant current led driver.
I am having trouble finding information for my question: Can LEDs receive a voltage above their recommended value if the current is constant?
Also, side question, if the current is constant at 600mA and the led's current takes 600mA, then I don't need a resistor?
update:
Thank you for all of your input. @mkeith was correct when saying "I think the point of confusion is that you don't understand the relationship between the power source and the load."
I was under the impression that only the value of the Amps through an led mattered. I thought that since the company suggested the driver with a minimum output voltage of 18V, when the LED that it was referenced from, had a voltage of 3-3.3V, that that meant the constant current is what mattered. I was asking if the higher voltage (18V from the driver vs. 3.3V of the LED) with the correct Amps would be okay.
I have com to realize why this driver was suggested. wiring the 3V LED in series to get about 18V maybe have been the intended use.
additionally, I better understand the difference between constant current and constant voltage and how the LED will control the amps (when constant voltage is applied) and the Volts (when constant current is applied)
Best Answer
The driver is inappropriate for the LED because the minimum voltage from the driver (18V) is greater than the minimum LED voltage at 600mA (3V). The driver is likely designed for LED arrays that have at least 6 dice in series, so 18V.
When you feed the particular LED die you mention with a constant current between 600 and 700mA you will get a voltage (assuming you have not destroyed the LED) that will be between 3V and 3.4V (or maybe the voltage is specified at a particular current).
If you do not exceed the recommended current, the LED voltage should not exceed the range given (it will actually drop a bit as the LED heats up).
You only get to pick either the voltage or the current. With an LED, you are expected to pick the current and the voltage across the LED will be a result of that current. If you tried to run the LED from a constant voltage supply you would have to find the voltage experimentally and it would not be stable (and could kill the LED).